Truck for mixing and delivery of blasting compositions

ABSTRACT

AN IMPROVED TRUCK FOR MIXING AND DELIVERY OF AMMONIUM NITRATE-FUEL OIL BLASTING COMPOSITIONS CONTAINING A SECOND SOLID FUEL IN ADDITION TO THE AMMONIUM NITRATE IS PROVIDED. THE TRUCK HAS SEPARATE STORAGE TANKS AND CONVEYORS FOR THE AMMONIUM NITRATE, FUEL OIL AND SECOND SOLID FUEL. THE CONVEYORS ARE CONNECTED TOGETHER FOR SIMULTANEOUS OPERATION WITH A HYDRAULIC DRIVE SYSTEM. THE SOLIDS ARE FED THROUGH AN AIR LOCK TO A MIXING CHAMBER WHERE THEY ARE MIXED WITH FUEL OIL AND ARE DISCHARGED FROM THE MIXING CHAMBER WITH PNEUMATIC PRESSURE. A VENT PIPE IS CONNECTED BETWEEN THE AIR LOCK AND THE SOLIDS OUTLETS FROM THE STORAGE TANKS AND RELEASES PNEUMATIC PRESSURE WHICH ESCAPES FROM THE MIXING CHAMBER THROUGH THE AIR LOCK WHICH ALLOWS THE SOLIDS TO BE FED TO THE MIXING CHAMBER IN ADJUSTABLE AND PRECISELY CONTROLLED AMOUNTS.

Sept. 20, 1971 1:..1. PEDERSON 3,606,267

' TRUCK FOR MIXING AND DELIVERY OF BLASTING COMPOSITIONS med Jan. 22. 1970 2 Sheets-Sheet 1 DONALD J. PEDERSON 2 INVENTOR.

HBYMAM ATTORNEY P 1971 o. J. PEDERSON 3,606,267

- TRUCK FOR MIXING AND DELIVERY OF BLASTING COMPOSITIONS Filed Jan. 22, 1970 2 Sheets-Sheet 2 FIG. 8 DONALD J. PEDERSON 36 INVENTOR.

FIG. 7 Y

ATTORNEY Patented Sept. 20, 1971 3,606,267 TRUCK FOR MIXING AND DELIVERY OF BLASTING COMPOSITIONS Donald J. Pederson, Tucson, Ariz., assignor to Hercules Incorporated, Wilmington, Del. Filed Jan. 22, 1970, Ser. No. 5,071 Int. Cl. 1301f 7/08 U.S. Cl. 259-6 Claims ABSTRACT OF THE DISCLOSURE An improved truck for mixing and delivery of ammonium nitrate-fuel oil blasting compositions containing a second solid fuel in addition to the ammonium nitrate is provided. The truck has separate storage tanks and conveyors for the ammonium nitrate, fuel oil and second solid fuel. The conveyors are connected together for simultaneous operation with a hydraulic drive system. The solids are fed through an air lock to a mixing chamber where they are mixed with fuel oil and are discharged from the mixing chamber with pneumatic pressure. A vent pipe is connected between the air lock and the solids outlets from the storage tanks and releases pneumatic pressure which escapes from the mixing chamber through the air lock which allows the solids to be fed to the mixing chamber in adjustable and precisely controlled amounts.

This invention relates to a transport, mixing and delivery truck which is a mobile manufacturing facility having the ability to mix and deliver a blasting composition comprising a blend of ammonium nitrate prills, a liquid fuel and particulate metal fuel to a blasting site in precisely controlled compositional ranges. In another aspect this invention relates to a mobile manufacturing facility having the capability of manufacturing blasting compositions of varying energies at on-site locations for delivery to a container or to a bore hole. In still another aspect, this invention relates to a mobile manufacturing facility for mixing and delivery of an explosive blasting composition having the highly desired safety feature of separate storage for each of the components of the composition prior to mixing of the components to form a blasting composition.

Bulk transport, mixing and delivery trucks for ammonium nitrate and fuel oil are well known. These trucks are highly suitable for mixing and discharging ammonium nitrate-fuel oil mixtures to a bore hole or to a container. A particularly suitable truck design for mixing and delivery of an ammonium nitrate-fuel oil mixture is disclosed and claimed in U.S. 3,424,438.

As is well known in the use of ammonium nitrate-fuel oil blasting agents, precise control of the blasting composition is required in order to achieve a suitable blasting agent. Attempts to employ the mixing and delivery truck disclosed in U.S. 3,424,438 to feed a solid material in addition to the ammonium nitrate to increase the energy of ammonium nitrate-fuel oil blasting agents have been unsuccessful. The problems encountered with attempting to feed a second solid material employing this mixing and delivery truck are fully described hereinafter.

The mixing and delivery truck of this invention constitutes an improved mixing and delivery truck over that of U.S. 3,424,438 for mixing of at least a second solid material with ammonium nitrate and fuel oil in precisely controlled amounts and for delivery of the resulting blasting composition to a bore hole or container.

Broadly, the improved transport, mixing and delivery truck of this invention comprises in combination a first solids storage tank, a first conveyor means extending axially of the first solids storage tank and mounted at the lower portion thereof, said tank having an inlet and an outlet, said outlet being in communication with the first conveyor means; a second solids storage tank having a second conveyor means extending axially of said tank and mounted in the lower portion thereof, said second SOlldS storage tank having an inlet and an Outlet, said outlet being in communication with the second conveyor means, a liquid feed tank and a liquid conveyor means connected thereto, pneumatic discharge means and means to provide air to said discharge means, drive means operatlvely connected to the first and second solids conveyors and to the liquid convey'or to impart, upon actuation thereof, simultaneous movement to the conveyors, a mixing chamber connected to said pneumatic discharge means and in communication therewith, said mixing chamber being connected to and in communication with the outlets of the first solids storage tank, the second solids storage tank, and the output of the liquid conveying means; isolation means intermediate the first and second solids storage tank outlets and the mixing chamber for substantially reventing pneumatic pressure from the pneumatic discharge from flowing into the outlets from the solids storage tanks while permitting solids to flow through the isolation means into the mixing chamber; and vent means for releasing pneumatic pressure escaping through the isolation means from the mixing chamber whereby the solids from the first and second solids conveyors flow from their respective outlets into the mixing chamber in precisely controlled amounts.

The following description and drawings will more fully illustrate this invention. In the drawings like symbols are used for like parts wherever applicable. Reference is made to U.S. 3,424,438 for description of the basic truck construction and operation which does not constitute the present invention.

FIG. 1 is a fragmentary schematic side elevational view illustrating portions of the improved mixing and delivery truck of this invention, partly broken away and partly in section.

FIG. 2 is an enlarged and elevational view as the truck appears from the right as viewed in FIG. 1 and with portions of the apparatus removed.

FIG. 3 is an enlarged fragmentary view partly broken away and partly in section taken along lines 3-3 in FIG. 1.

FIG. 4 is an enlarged fragmentary section taken along line 44' of FIG. 3.

FIG. 5 is an enlarged fragmentary section taken along line 55' of FIG. 2.

FIG. 6 is a fragmentary section taken along line 6-6 of FIG. 5.

FIG. 7 is a schematic view illustrating the auger for the first solids material conveyor.

FIG. 8 is a schematic view illustrating the auger for the second solids material conveyor.

In FIGS. 1 and 2 the improved mixing and delivery truck of this invention is illustrated. As shown, the truck includes a truck body 10 having a cab 12, an engine compartment 14, a rearwardly extending frame 16, the truck being capable of movement as by wheels 18. The first solids storage feed apparatus is comprised of a compartmented storage tank 20 having three sections 22, 24 and 26, each storage section being separated from the other as by dividing walls 28. Each storage section has an inlet 22a, 24a and 26a. The bottom walls 30 of storage tank 20 slope inwardly and merge into an axially extending arcuate bottom 32, which houses a first material conveyer means therein which in this instance is auger 36. Auger 36 serves upon actuation, to feed the first solid material towards a first outlet 38, said outlet 38 being in communication with the lower portion of storage tank 20. Auger 36 extends beyond the forward end 37 of the first solids storage tank 20 through an anger housing 39 having an arcuate bottom, said auger housing terminating at outlet 38. Directly below outlet 38 and in communication therewith is an isolation means which is employed to prevent pneumatic pressure from the pneumatic discharge means from passing into the storage tanks. The isolation means in this instance is rotary air lock 40, more fully described hereinafter and by reference. Auger 36 extends beyond the axial length of the first solids storage tank 20 through auger housing 39 and terminates at outlet 38 located above the rotary air lock 40.

The second solids storage tank 44 is positioned aft of first solids storage tank 20 as shown in FIG. 1. The bot tom side walls 46 of the second solids storage tank 44 slope inwardly and merge into a bottom 48 which in this instance is flat. As is clearly shown in FIGS. 3 and 4 a second solids conveyor, and in the present instance an anger 50, is housed directly above the bottom 48 of storage tank 44 and extends the axial length of the bottom 48 of the tank. The bottom 48 of the second solids storage tank 44 has a central outlet 52 directly above and in communication with auger 36 at a point forward of the forward end 37 of storage tank 20 which is forward of the solids inlets to auger 36. Auger 50 has a central shaft (not shown) journaled at opposite ends of the second solids storage tank 44. A hydraulic pump (not shown) contained within housing 51 is used to eflect rotation of auger 50 through gear 53 secured to anger 50. Auger 50 is driven simultaneously with auger 36 and the liquid conveying means. Auger 50 has right hand flights 54 and left hand flights 56 (see FIG. 8) which move the second solid material from both sides of storage tank 44 toward central outlet 52. In order to aid in control of the amount of solids passed into auger 36 of the first solids storage tank and anger 50 of the second solids storage tank, metering shields 58 are superposed above the respective augers and are held in place by support members 60. The metering shields 58 form inlets for the solids into the conveyors and aid in control of the amount of solids which pass from the solids storage tanks into the augers 36 and 50.

In operation of the improved mixing and delivery truck of this invention solids from the second solids storage tank such as particulate aluminum are dropped through central outlet 52 of the second solids storage tank 44 into auger 36 as a result of the conveying action of anger 50. Auger 36 then moves the combined solids to outlet 38 where the combined solids drop into the air lock 40 and are then passed into mixing chamber 62. Fuel oil from fuel oil tanks 64 is fed by pump means 66 through conduits 68 into two injection spray nozzles 70 positioned on opposite sides of mixing chamber 62. The resulting blasting composition is discharged under pneumatic pressure into a bore hole. Pneumatic pressure is supplied to mixing chamber 62 by a blower 72 which is connected by a conventional power take off shaft extending from the transmission of the vehicle (not shown) to a power take off gear box 74. The blower is mounted on the frame 16 of the truck 10. A conduit 76 connects the air discharge side 78 of blower 72 to the inlet end 80 of the mixing chamber 62.

Interposed between the mixing chamber 62 and outlet 38 is an isolation means which in this instance is an air lock 40. Details on the air lock are completely set forth in US. 3,424,438 at column 3, lines 50-75 and column 4, lines 1-16 and are illustrated in FIGS. and 6 of that patent. Air lock 40 has radially projecting vanes 41 which engage a cylindrical housing 43 and function to divide the housing into a series of compartments 45. The function of the isolation means is to prevent pneumatic pressure from the pneumatic discharge from flowing into the outlet(s) of the solids storage tanks, while permitting solids to flow through the isolation means into the mixing chamber. Interposed between air lock 40 and solids outlet 38 is a vent pipe 82. The spatial relationship between the vent pipe 82, air lock 40 and solids outlet 38 is shown in FIGS. 5 and 6. The necessity of the vent pipe 82 interposed between the air 109k 40 and feed outlet 38 will be fully cussed hereinafter. Vent pipe 82 exhausts into the top of the second solids feed tank 44. Vent pipe 82 can be vented to the atmosphere if desired.

In FIGS. 7 and 8 schematic views of auger 36 and auger 50 are shown. When employing the design heretofore described in which the second solids conveyor feeds the second solid to an outlet 52 whereby the second solid drops into the first solids conveyor for ultimate conveyance into the mixing chamber, it is necessary that the first conveyor have sufficient capacity to continuously receive and convey all of the second solid fed to the first conveyor at a rate at least equivalent to the feed rate of the second solid material. In order to maintain sufficient space within the first solids conveyor the pitch of the flights of anger 36 is increased at various intervals along the length of the auger 36. The pitch of the flights is the greatest at the forward end of the auger which receives the second solid material from the second solids conveyor. If the rate of removal of the second solid material from the point of its reception below outlet 52 by the first solids conveyor is not equal to the rate at which the second solid is fed to the first conveyor, the composition of the solids being fed into the mixing chamber will be in error. Thus, if auger 36 is full at the receiving point for the second solid material, feeding accuracy is lost.

The foregoing description is directed to the improved truck of this invention. Details of the pumping and valving system for synchronous drive of the conveyor means for conveying both a first solid, a second solid and a liquid are substantially the same as the pumping and valving system of US. 3,424,438 for a first solid and a liquid with the addition of a third hydraulic pump suitably connected to the system for simultaneously driving the second solids conveyor. Reference to FIG. 2 of US. 3,424,438 for illustrations of pump means, fuel oil storage and a valving arrangement which is readily adapted to be employed in the improved truck of this invention is hereby made.

The design of the improved mixing and delivery truck of this invention is based upon the solution to the problem of how to accurately and safely feed a second solid material employing the basic concepts for mixing and dclivery of an ammonium nitrate-fuel oil explosive composition as described in the prior art referred to herein. The problem of accurately feeding a second solid material and the solution to the problem is further described with reference to the foregoing drawings and description so that the present invention can be clearly understood. Feeding a second solid material employing the prior art mixing and delivery truck by charging different solid materials to different storage compartments in the first storage tank in the truck described and using a single conveyor is not satisfactory. Poor accuracy in control of the individual solid feed rates results from the conveyor emptying out the first storage compartment 22 of storage tank 20 at a much greater rate than the second and third storage compartments 24, 26. The first storage compartment empties faster than the second and third storage compartments since the conveyor partially or completely fills as it receives solids below the first storage compartment. This partially or completely filled conveyor restricts fiow of solids from the second and third compartments into the conveyor making delivery of precisely controlled amounts of each solid practically impossible.

Initial attempts to obtain accurate feeding of a second solid material included the addition of a second solids storage tank such as storage tank 44 and a separate conveyor such as auger 50. This modification to the truck was made as shown in FIG. 1 of the foregoing drawings. This modification, alone, did not achieve the desired control in feeding of the second solid material. Feeding of the second solid material directly to the air lock from the second solid conveyor was not satisfactory. This modification is not shown in the foregoing drawings.

Solution to the problem of accurately feeding a second solid material was achieved after the discovery that the small amount of air trapped with the compartments 45 of rotary air lock 40 which escaped into the conveyors and storage tanks during rotation of the air lock was sufficient to cause aeration of the solids in the conveyor Which resulted in back-up of solids in the conveyors filling them up, and also caused blowing of solids from one conveyor to the other. While this escaping gas had little or no effect on control of a one component solid feed system, it made control of a two solid feed system impossible. It was found necessary to provide a vent means, preferably intermediate the air lock and the outlets from the solids conveyors, to relieve the air pressure escaping through the isolation means into the conveyors and storage tanks. Once this air vent had been installed, accurate control of feeding a second solid material, employing a second solid storage tank and second conveyor means, was achieved.

Thus, in its broadest aspect, the mixing and delivery truck of this invention comprises the basic mixing and delivery truck of U.S. 3,424,438 wherein the improvement comprises a second solids storage tank, a second conveyor means extending axially of said tank and mounted in the lower portion thereof, said second solids storage tank having an inlet and an outlet, said outlet being in communication with the second conveyor means and with the mixing chamber, drive means connected to said second conveyor to impart, upon actuation thereof, movement to said second solids conveyor simultaneously with movement of said first solids conveyor and said liquid fuel conveyor and vent means for releasing pneumatic pressure escaping through the isolation means from the mixing chamber, permitting the solids from the first and second solids conveyors to fiow from their respective outlets into the mixing chamber in precisely controlled amounts.

The foregoing description is illustrative of the improved mixing and delivery truck of this invention. While the truck of this invention is particularly designed to mix and deliver two solid materials which are solid oxidizing agents and solid fuels and one liquid fuel, it is not so limited. Additional solids can be fed by adding additional solid storage tanks and conveying means for each solid to be employed. Likewise additional liquids can be added employing additional liquid storage tanks and conveying means such as additional hydraulic pumps. The mixing and delivery truck of this invention is particularly adaptable for mixing ammonium nitrate-fuel oil explosive compositions containing a particulate metal fuel such as aluminum for increasing the energy of the explosive composition. The mixing and delivery truck of this invention is also readily adaptable by simple changes in hydraulic pumps and/or gear ratios to adjust the explosive composition being mixed and delivered to a bore hole' from an optimum bottom load mixture containing as high as about 16% by weight of a particulate metal fuel to an optimum top load blasting composition containing no metal at all. Thus, the mixing truck of this invention makes it possible to deliver predetermined and variable amounts of at least a second solid material by control of the feed rate of the second solid material.

While ammonium nitrate is the generally preferred oxidizer material, other oxidizer salts such as sodium nitrate, calcium nitrate, mixtures thereof and the like can be employed.

Suitable liquid fuels include fuel oil, paraffin oil, dinitrotoluene oil, ethylene glycol, and the like. These fuels can be employed separately, as mixtures, and can be employed with water.

Illustrative particulate metal fuels which can be employed as energizers for the explosive compositions include aluminum, silicon, ferrosilicon, ferrophosphorus, and mixtures thereof. In addition to the metal fuels other solid fuels such as sugar or coal can be employed. Thickening agents or gums can be admixed with the fuels for mixing and delivery with the fuels to the mixing chamber in forming the explosive composition.

What I claim and desire to protect by Letters Patent 1. In a storage, mixing, and mixture delivery apparatus comprising in combination a first storage tank having a first solid material conveyor means extending axially of the tank and mounted at the lower portion thereof, said tank having an inlet and an outlet, said outlet being in communication with said first conveyor; a liquid feed tank and a liquid conveying means connected thereto, pneumatic discharge means and means to provide air to said discharge means, drive means operatively connected to said first solid material conveyor to impart, upon actuation thereof, simultaneous movement to said conveyor, a mixing chamber connected to said pneumatic discharge means and in communication therewith, said mixing chamber being connected to and in communication with the outlet of said first solid material storage tank and to the output of the liquid conveying means, and isolation means intermediate said mixing chamber and said first solid material outlet for substantially preventing pneumatic pressure from the pneumatic discharge from flowing into the outlet from the solids storage tank, the improvement comprising a second solid material storage tank having a second conveyor means extending axially of said tank and mounted in the lower portion thereof, said outlet being in communication with said second conveyor means and with said mixing chamber, drive means operatively connected to said second conveyor means for imparting actuation to said second conveyor means simultaneously with said first conveyor means and said liquid conveying means, and vent means for releasing pneumatic pressure escaping through the isolation means from the mixing chamber permitting the solids from the first and second solids conveyors to flow from their respective outlets into the mixing chamber in precisely controlled amounts.

2. The storage, mixing and delivery apparatus of claim 1 in which the vent means is a vent pipe intermediate the isolation means and the first and second storage tank outlets.

3. The storage, mixing and delivery apparatus of claim 1 in which the second solids storage tank outlet is in communication with said second conveyor means and with the first conveyor means whereby the output from the second solids conveyor is delivered into the first solids conveyor.

4. The storage, mixing and delivery apparatus of claim 3 in which the first conveyor is an auger mounted for rotation in the bottom of the first storage tank, the bottom of the first storage tank being extended forming an extended auger housing having an outlet in communication with the auger and with mixing chamber and hav ing an inlet for the second solid material, said auger having sections of flights of at least two varying pitches, the section of auger flights below the inlet of the second solid material in the auger housing and terminating at the outlet to the mixing chamber having a greater pitch than the flights of the auger extending axially of the first storage tank.

5. The storage, mixing and delivery apparatus of claim 4 in which the vent means is a vent pipe intermediate the isolation means and the auger housing outlet.

References Cited UNITED STATES PATENTS 2,094,839 10/1937 Gassman 259-151 2,161,553 6/1939 Westberg 259151 3,168,291 2/ l 965 Knoedler 2599 3,310,293 3/1967 Zimmerman 259-151 3,424,438 1/ 1969 Knotts 2594 ROBERT W. JENKINS, Primary Examiner U.S. Cl. X.R. 259-151 

